1. Field of the Invention
This invention relates to a filter for use in a storm sewer catch basin equipped with a top grate. The ground water flows through the grate into the catch basin and into the sewer line. Before the ground water flows into the sewer line it needs to be filtered free of pollutants.
2. Description of the Prior Art
In the past this has been accomplished by placing a filter bag below the grate and inside the catch basin. In U.S. Pat. Nos. 5,575,925 and 5,372,714 the filter bag is held in place by the weight of the grate against the lip of the basin opening. When the bag fills with the weight of filtered solids the bag tends to be pulled past the original position of depth. When the bag is emptied the filter bag is further pulled down into the grate risking the spilling of solids into the basin and the contamination of the sewer line. The slipping of the filter sack into the basin is prevented by the insertion of metal rods into flaps which extends away from the grate. This is an unnecessary expense in the manufacturing of the filter bag flaps, and materials, and labor.
Other filter bags which are below the grate and inside the catch basin require expensive support devices. In U.S. Pat. Nos. 6,149,803 and 5,849,198, the catch basin filter requires complex framing and supports which are unnecessary and expensive to manufacture, ship, and install. U.S. Pat. No. 5,849,198 describes a filter attached to the grate by a mechanical means such as chains or rods attached to a frame supporting a filter cartridge. These devices are unnecessary and expensive to manufacture and ship, and labor intensive to install. For the above reasons there is a need for a catch basin filter that is easy to install, environmentally safe to empty, and inexpensive to manufacture.
Our invention is a removable filter for a storm sewer catch basin equipped with a removable top inlet grate. The filter is typically composed of a porous geo textile fabric. The typical embodiment of our filter consists of a filter bag attached to the grate and suspended inside of the catch basin. The invention is an attachment means of holding a filter in place on the grate both during filtration and during filter removal. This prevents unnecessary contamination of the catch basin during service. The attachment means holds the basin filter in position by a variable opening in the top of the filter bag that comprises an opening size smaller than the grate and thereby couples the filter bag and the inlet grate together. When the filter is removed, the filter bag and grate are both removed as one unit from the catch basin. This prevents the filter from slipping free and dumping solids into the catch basin during both filtration and filter removal.